ST_NRings - Amazon Redshift
SyntaxArgumentsReturn typeExamples

Amazon Redshift will no longer support the creation of new Python UDFs starting November 1, 2025. If you would like to use Python UDFs, create the UDFs prior to that date. Existing Python UDFs will continue to function as normal. For more information, see the blog post .

ST_NRings

ST_NRings returns the number of rings in an input geometry.

Syntax

ST_NRings(geom)

Arguments

geom

A value of data type GEOMETRY or an expression that evaluates to a GEOMETRY type.

Return type

INTEGER

If geom is null, then null is returned.

The values returned are as follows.

Returned value Geometry subtype

0

Returned if geom is a POINT, LINESTRING, MULTIPOINT, or MULTILINESTRING subtype

The number of rings.

Returned if geom is a POLYGON or MULTIPOLYGON subtype

The number of rings in all components

Returned if geom is a GEOMETRYCOLLECTION subtype

Examples

The following SQL returns the number of rings in a multipolygon. 

SELECT ST_NRings(ST_GeomFromText('MULTIPOLYGON(((0 0,10 0,0 10,0 0)),((0 0,-10 0,0 -10,0 0)))'));

 st_nrings
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